The present invention pertains to a recliner mechanism for a seat assembly having an eccentric pivot pin for the seat back to enable the position of the seat back pivot to be adjusted to eliminate back lash in the recliner mechanism gears.
Motor vehicle seat assemblies are often provided with a recliner mechanism to enable the seat back to pivot about a lateral axis to enable the angle of the seat back to be adjusted for comfort of the occupant. Furthermore, the front seat assembly of two door motor vehicle includes a seat back that can be rotated forward from its normal use position to a forward dump position to improve the accessibility to the area behind the front seat.
One recliner mechanism structure is operable with a seat back structure having a pair of arms extending downward along the two sides of the seat back that are pivotally connected to the lower seat frame. The seat back support arm on one side of the seat assembly typically has a plurality of gear teeth along a curved path concentric about the seat back pivot. The gear teeth form a sector gear and mesh with a pinion gear pivotally connected to the lower seat frame for rotation about an axis generally parallel to the axis about which the seat back rotates. The recliner includes a releasable lock mechanism to hold the pinion gear from rotation and, due to the meshing of the pinion gear teeth with the sector gear teeth, the seat back is thus locked in position. If desired, a sector gear and pinion gear can be provided on both sides of the seat back and connected to a common release lever to simultaneously release both sides of the seat back to adjust the seat back angle.
However, due to manufacturing variation in the production of the recliner mechanism components, the gear teeth do not always fully mesh with one another. As a result, there is backlash between the gears, resulting in a vibration and rattle of the seat back which can annoy vehicle occupants and produce customer complaints.
It is an object of the present invention therefore, to provide a means by which the backlash between the sector gear and pinion gear in a seat back recliner mechanism can be eliminated.
According to the present invention, one of the seat back or pinion gear pivots is formed with an eccentric pivot pin. During assembly, the eccentric pivot pin is rotated about its concentric axis so as to move one pivot toward or away from the other pivot until the pinion and sector gears are in a proper meshing relationship. Once the proper mesh is achieved, the eccentric pivot is secured to the lower seat frame to fix the position of the eccentric pivot.
It is a further object of the present invention to provide a method of securing the pivot pin to the lower seat frame in a manner that prevents rotation of the pivot over the life of the seat assembly.
It is a feature of the present invention to form the eccentric pivot as a rivet with the plain or tenon end of the rivet knurled. Once the pivot has been rotationally positioned, the knurled end of the rivet is upset using an orbital riveting process that forces the knurled teeth of the rivet into the seat frame to prevent rotation of the pivot.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.